Offshore oil-drilling rig and methods for installing same on an offshore oil-drilling site

Abstract

An offshore oil-drilling rig comprising a deck mounted mobile on legs, each leg including a support base on the sea floor and a caisson open at its base and designed to penetrate into the sea floor. Each caisson is arranged inside the leg and is mobile along the axis of the leg between a retracted upper position and a projecting lower position at which it is anchored on the sea floor. The invention also concerns methods for installing such a rig on an oil-drilling site.

Description

CROSS REFERENCE TO RELATED APPLICATION[0001]This is a 35 U.S.C. §§371 national phase conversion of PCT / FR2005 / 002379, filed Sep. 26, 2005, which claims priority of French Application No. 0410545, filed Oct. 6, 2004. The PCT International Application was published in the French language.BACKGROUND OF THE INVENTION[0002]The present invention relates to an offshore production platform and methods of installing such a platform on a production site.[0003]Jackup-type offshore production platforms, such as oil platforms for example, generally comprise legs, usually three in number, bearing on the seabed, and a deck mounted so as to be able to move with an adjustable height on the legs and carrying, in particular, production equipment and living premises.[0004]The bottom end of each leg is fitted with a foot or stand designed to bear on the seabed when the platform is installed on a production site. This foot or stand of each leg provides a limited area of contact with the seabed, allowing ...

AI Technical Summary

Benefits of technology

[0011]The invention is intended to overcome these drawbacks by proposing an offshore production platform whose cost of installation on an offshore site is reduced.

Problems solved by technology

But, given the size of such piles, this measure is a lengthy and costly operation because it requires intervention of heavy equipment whose operating cost is extremely high.

During transportation of the preassembled platform from the erection site to the production site, either by floating the platform or by barge, these caissons, which are several meters high, are in the water and create high resistance to platform forward movement and thus additional energy expenditure.

Furthermore, this arrangement creates problems, when mounting the caissons onto the bottom end of the legs of the platform.

The bottom end of each leg is submerged in most cases, so much so that handling these caissons requires heavy, complex infrastructure, due to the volumes to be controlled, because these caissons have a diameter of around 17 to 20 meters and a height that can attain several meters.

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